In the art, single-sided cutting inserts for cutting metal and particularly chamfering and counterboring insert for drills and respective tools are known. For example, referring to FIG. 1, there is shown a drill with two such inserts. Each insert is generally rhomboidal having opposing top and bottom surfaces and a peripheral side surface extending between the top and bottom surfaces. The peripheral side surface comprises two major side surfaces of which each has two major side surface sections of which only one defines a cutting edge with the top surface. Each two major side surface sections meet at a transition edge. The cutting insert has a 180° rotational symmetry about a first axis extending through the opposing top and bottom surfaces (see FIG. 2). The inserts are supported in the drill via two abutment surfaces and a fixation screw.
DE-A-3610016 relates to a drill with chip disposal flutes, at least one first cutting edge provided at the tip, and a ring which is arranged on the drill and is provided with at least one second cutting edge which is arranged at a certain distance from the first cutting edge in order to chamfer, countersink or counterbore the hole drilled by the first cutting edge. The ring is provided with recesses which are arranged opposite the flutes and form chip passages with the latter.
The prior art single-sided cutting inserts are indexable in one plane only, and have at most two cutting edges per direction of rotation of the drill. Moreover, the transition edge at which the major side surface sections meet prevents clearance between the insert and the workpiece, thereby limiting the depth of cut. Furthermore, clamping relies on the fixation screw and two abutment surfaces only.